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# Can the air pressure in tank be higher than the compressor outlet pressure?3

## Can the air pressure in tank be higher than the compressor outlet pressure?

(OP)
I am trying to simulate the performance of a compressed air energy storage system.
I have modeled the compressor using the following equation

The compressed air pressure in the tank is changing according to the following equation

The outlet pressure of the compressor is 15 bar and the maximum air pressure limit of the compressed air tank 30 bar with a constant volume. By running the simulation and supplying power to the compressor, more compressed air mass flow rate is generated and fed to the air tank and the pressure increases in the tank reaching 25 bar in my case. Can the air pressure in the tank exceeds the maximum outlet pressure of the compressor ? Is there like a non-return valve or something for that ?

### RE: Can the air pressure in tank be higher than the compressor outlet pressure?

#### Quote (Ameen1985)

Can the air pressure in the tank exceeds the maximum outlet pressure of the compressor ?

Did you actually do any reflective thinking before writing that?

The answer on the data provided is clearly no, otherwise you've found the answer to the worlds energy problems....

Ypour model clearly doesn't recognise the physical facts of life and therefore needs to be redesigned.

Not only will the compressor simply stall or stop flowing or lift the relief valve, but the energy required changes as the pressure rises. Maybe your formula recognises that - I can't say, but it's not a fixed thing and changes as the air pressure increases.

The only way pressure can rise in the "tank" or Pressure vessel is if you inject more mass or the temperature rises.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: Can the air pressure in tank be higher than the compressor outlet pressure?

What LittleInch said.

By way of example:

Some of the oil circuit breakers I used to operate had pneumatic closing mechanisms.

If the breaker's air system was in a good and tight condition and pumped itself up overnight due to air contraction in the receiver, the air pressure in the receiver would be at maximum right at sunrise.

As the mechanism box and air receiver were heated by the sun over the course of the day, the air in the receiver would expand due to insolation, but due to its being confined in the receiver the air pressure in said receiver would slightly exceed the compressor discharge pressure sometime mid-afternoon, but not usually enough to cause the receiver safety valve to blow off.

There is almost always a check or non-return valve in the piping between the compressor and the air receiver so that full receiver pressure is not continuously applied to the compressor discharge valve or valves.

Additionally, any but the smallest compressors typically have an unloading system that bleeds off the compressor discharge pressure upon shutdown, such that upon subsequent restart the compressor has no work to do and reaches full operating speed promptly.

Beyond that, it seems the OP needs to give his head a shake.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

### RE: Can the air pressure in tank be higher than the compressor outlet pressure?

#### Quote:

The only way pressure can rise in the "tank" or Pressure vessel is if you inject more mass or the temperature rises.

The OP's model doesn't understand that you can't inject more mass from a lower pressure to a higher pressure.

TTFN (ta ta for now)
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### RE: Can the air pressure in tank be higher than the compressor outlet pressure?

All utility air compressors would have check valve on final discharge to prevent reverse flow when the compressor goes into unload mode.

### RE: Can the air pressure in tank be higher than the compressor outlet pressure?

They say there are no bad questions, but they're wrong.

Yes, the pressure in the tank could be higher than the compressor discharge pressure, but something other than the compressor is needed to cause that.

### RE: Can the air pressure in tank be higher than the compressor outlet pressure?

(OP)
As you said, I (the OP) need to give my head a shake.
The used air receiver equation in my model doesn't depend on the compressor pressure. As more air mass flows to the air receiver, its pressure increases. Then, I found it exceeds the air compressor discharge pressure which is not possible because the compressor is responsible for charging the air into the vessel. However, I thought may be there is a mechanism, valve, or anything can allow inject more mass from a lower pressure to a higher pressure.

### RE: Can the air pressure in tank be higher than the compressor outlet pressure?

#### Quote (Ameen1985)

However, I thought may be there is a mechanism, valve, or anything can allow inject more mass from a lower pressure to a higher pressure.

There is, it's a second compressor, or second compressor stage in a multi-stage compressor.

Good Luck,
Latexman

### RE: Can the air pressure in tank be higher than the compressor outlet pressure?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: Can the air pressure in tank be higher than the compressor outlet pressure?

If you can generate enough velocity and then slow the flow there will be a pressure rise. The trouble is that you need to start with a lower pressure to generate the high velocity and then create a pressure rise when the flow is suddenly stopped. I believe this is called recompression.

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